My 1992 honda civic won't start when it's hot; by "hot" I mean like when I have driven awhile, shut if off to fill it up with gas and try to restart, and even when it's been sitting in the hot sun for awhile. Any suggestions are welcome. Thank you.

That is characteristic of a failing Main Relay. Cold solder joints open on the PCB, when the ambient temperature goes up during the day (especially when it has been sitting in the sun). Try installing a new Main Relay, located under the dash.